To connect your Apple or Google account to an existing Upstock account:
Log in to Upstock with the email and password you normally use
Go to the Personal Profile setting, which you can access from the menu at the bottom left of the page
Select Connect Apple or Connect Google
Managing connected accounts
You can disconnect your Apple or Google account at any time. Just go to Settings › Profile and click the connected account. You'll be shown details for the connect account, plus an option to disconnect.